Advices for Orchard mobile site

Hello all,
Our company is studying to use Orchard to serve the mobile version of our website. The website is an 6 years old design. In a clasic aspx and a very primitive css.

So I don't want to re-theme that. Fortunatelly, I staid two years making isolated layers, and I can reuse some logic. In my dreams, I will migrate the whole website to Orchard. So, I want to profit the situation to start with the mobile version.

But I didn't find tutorials or articles about adapting Orchard to mobile.
If it is only modifying any responsive design, then I need to migrate now all the website :S